Modeling and Control of Dielectric Elastomer Actuator Based on Neural Ordinary Differential Equation and Nonlinear Model Predictive Control
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摘要: 针对介电弹性体驱动器(Dielectric elastomer actuator, DEA)建模与控制的挑战性问题, 提出基于神经网络常微分方程(Ordinary differential equation, ODE)和非线性模型预测控制(Model predictive control, MPC)的DEA动力学建模与跟踪控制方法. 首先, 基于神经网络ODE建立DEA的动力学模型以描述其复杂的动态行为. 然后, 基于所建立的DEA动力学模型, 设计非线性模型预测控制器实现其跟踪控制目标. 最后, 在所搭建的实验平台上进行一系列跟踪控制实验. 在所有实验结果中, DEA的运动均能很好地跟踪目标轨迹, 且相对均方根误差均不超过3.30%, 说明了所提动力学建模与跟踪控制方法的有效性.Abstract: For challenging problems in modeling and control of dielectric elastomer actuators (DEA), this paper proposed dynamic modeling and tracking control methods for a DEA based on the neural ordinary differential equation (ODE) and nonlinear model predictive control (MPC). First, a dynamic model of the DEA was established based on the neural ODE to describe its complicated dynamics behavior. Then, based on the established dynamic model of the DEA, a nonlinear model predictive controller was designed to realize its tracking control objective. Finally, a series of tracking control experiments were conducted on the built experimental platform. In all experimental results, the motion of the DEA can track the target trajectory well, and all relative root-mean-square-errors are no more than 3.30%, which illustrates the effectiveness of proposed dynamic modeling and tracking control methods.
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表 1 第1个实验方案中所有实验的相对均方根误差
Table 1 $E_R$ for all experiments of first experimental scheme
$m$ $a_m$ (kV) $E_R$ (%) 1 5.0 3.12 2 6.0 1.53 3 7.0 1.55 4 8.0 2.16 表 2 第2个实验方案中所有实验的相对均方根误差
Table 2 $E_R$ for all experiments of second experimental scheme
$m$ ${\psi}_m$ (Hz) $E_R$ (%) 1 0.2 1.82 2 0.6 2.10 3 1.0 2.50 4 1.4 1.89 表 3 ${{N}_{p}}$和${{N}_{c}}$取值对控制精度、单步运行时间和实时性的影响
Table 3 Influences of values of ${{N}_{p}}$ and ${{N}_{c}}$ on control accuracy, single-step running time and real-time performance
${{N}_{p}}$ ${{N}_{c}}$ $E_R$ (%) $T_c$ (s) 实时性 2 1 3.26 $5.08\times {10^{ - 3}}$ 满足 4 2 2.83 $8.39\times {10^{ - 3}}$ 满足 5 2 1.88 $8.91\times {10^{ - 3}}$ 满足 6 4 — $1.85\times {10^{ - 2}}$ 不满足 -
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